1. Field of the Invention
The present invention relates to a heat-dissipating fan having a simplified structure and being capable of eliminating the magnetic resistance on the magnetically conductive path, thereby providing an improved rotational torque.
2. Description of the Related Art
FIG. 7 of the drawings illustrates a conventional heat-dissipating fan structure comprising a casing 90 having an axle seat 91 to which a stator bobbin 92 is mounted. The stator bobbin 92 comprises a winding 923 wound therearound, an upper pole plate 921, and a lower pole plate 922. Extended through the stator bobbin 92 is a metal axle tube 93 in which a bearing 94 is mounted for rotatably holding a shaft 96 of a rotor 95. A permanent magnet 97 is mounted to the rotor 95 and comprises a north pole and a south pole that cooperates with a magnetic force generated in the edge of the upper and the lower pole plates 921 and 922 for generating a repulsive force, thereby driving the rotor 95 to turn.
In such a conventional heat-dissipating fan structure, the stator bobbin 92 is complicated and thus troublesome to manufacture as it has a winding 923 wound between the upper pole plate 921 and the lower pole plate 923. In addition, since the stator uses a metal axle tube 93 to form a magnetically conductive path together with the upper pole plate 921 and the lower pole plate 922, magnetic resistance exists in the material per se, which, in turn, results in an increase in the overall magnetic resistance, and the rotational torque is adversely affected accordingly.
It is an object of the present invention to provide a heat-dissipating fan structure that has fewer elements and thus has a smaller volume for easy manufacture and processing.
Another object of the present invention is to provide a heat-dissipating fan structure that directly creates a mutual repulsive force between a magnetic field generated by the winding and the permanent magnet having a south pole and a north pole to thereby eliminate the magnetic resistance on the magnetically conductive path, thereby providing an improved rotational torque.
A heat-dissipating fan structure in accordance with the present invention comprises a frame having a through-hole. An air inlet and an air outlet are respectively defined in two ends of the through-hole. A support section is provided in an end of the through-hole and at least two sets of windings are engaged on the frame. An IC control means is mounted on the frame and electrically connected to the windings. A rotor comprises a shaft and plural blades, and a permanent ring magnet is mounted around the blades. An end of the shaft is rotatably received in the support section of the frame. A repulsive magnetic force is directly created between the permanent ring magnet and the windings of the frame to drive the rotor to turn.
Other objects, specific advantages, and novel features of the invention will become more apparent from the following detailed description and preferable embodiments when taken in conjunction with the accompanying drawings.